SHOULDER GIRDLE AND ANTERIOR LIMB 513 
siderable portion of the girdle-forming cells is included so that a 
girdle of the size shown in figure 28 develops at the place of 
implantation. 
2. Transplantation of the ventral zone rudiment of the girdle and 
the ventral portion of the limb mesoderm. It has been shown in 
table 5 that extirpation of the mesoderm within the area 
a-e X 4-8 resulted in the formation of a girdle without a ventral 
zone (fig. 29). In this excision the ventral portion of the limb 
rudiment was included. This same area was transplanted in 
order to ascertain whether it would develop into a limb and a 
girdle consisting of only the ventral zone. Fifteen such trans- 
plantations were made. All developed limbs, of which ten 
showed reduplications of the hand; four were abortive and one 
normal. Three such cases were sectioned twenty-two days after 
the operation. The sections showed that only the ventral zone 
of the girdle was present with the limb (figs. 15 and 32). The 
limbs which resulted from these transplants developed from only 
a portion of the limb rudiment, showing thereby the equipoten- 
tiality of this system. The failure of the dorsal zone of the 
girdle to develop offers additional evidence to show the non- 
equipotentiality of the girdle rudiment. 
3. Transplantation of the dorsal zone rudiment of the girdle and 
the dorsal portion of the limb mesoderm. This series of experi- 
ments consisted of the transplantation of the area a-e < 1-4 
(text fig. 1) including the ventral halves of the somites, the pro- 
nephros, and the dorsal segment of the limb mesoderm. ‘Ten 
such transplants gave rise to limbs, eight of which showed either 
reduplications of the hand alone or of both the forearm and hand. 
An examination of the girdles which had developed in these ex- 
periments shows that they are composed almost entirely of a 
dorsal zone (figs. 16 and 33), which, while somewhat smaller 
than the dorsal zone of a normal girdle, are nevertheless com- 
plete with respect to their elements, viz., suprascapula and | 
scapula. The presence of a very small portion of the ventral 
zone in the girdle shown in figure 33 is no doubt due to the inclu- 
sion in the transplant of some of the cells which are to form the 
ventral zone, yet the failure of these cells to form a complete 
